Posted by: @l8again

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My Valliant 7kW heat pump has been installed now for just over a month. It is running in the manual heating mode on a Level 0.3 heat curve on a radiator system with weather-compensation (flow temp 25C at OAT +10). Combined daily COP is usually in the range 4.4 to 5.2.

The piece of the jigsaw that my 75 year old brain is struggling with is this - ‘what function does the set temperature in the App have in the above set up’? It is currently set at 19C with an actual room temp of 19.8C.

It depends on what 'room temperature mod(ification)' the circuit has been set to.  Its explained (not particularly well) in the sensocomfort manual on page 4 and 11.

1. If Room temp mod is 'inactive' then the system is operated in pure weather compensation mode.  In this mode the flow temperature is not influenced at all by room temperature, it is set purely according to the WC curve as a function of OAT.  All that the 'set temperature ' does is to shift the WC curve (which is designed for 20C room temperature if correctly set up) laterally, as set out on page 4.

2. If Room temp mod is 'active' then the above applies but in addition the system tweaks the flow temperature a bit according to the measured room temperature.  The algorithm is not given, its a relatively small tweak and its not clear whether there is any machine learning.  Basically it works on top of a reasonably well adjusted WC curve as a sort of limited autoadaption.

3.  If Room temp mod is 'expanded' then (1) but in addition the system will shut down completely if the room temperature exceeds the set temperature by 2/16C.  Basically it acts as a limiter.

I run mine in mode 1 for almost all the season, switching to mode 3 at the very end of the season where solar gain otherwise tends to cause overheating.  Many say mode (2) is also good, but I found that, for my house, pure WC gave by far the best comfort and stability.  So I simply adjusted the WC level until the room temperature was what I wanted, and left it.  Apart from to check the outside temperature (its more or less impossible to tell since I installed the heat pump) I touch the controls only a couple of times per year.

Hope that helps, feel free to ask further questions.

@jamespa Thanks that’s very helpful. My installer has left room temp mod inactive. The handover comprised two short phone calls so I am still ‘self learning’.

Posted by: @l8again

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Thanks that’s very helpful. My installer has left room temp mod inactive

Thats arguably a sign of a good installer - they understand that weather compensation is all important and that it may need to be tweaked.

There is a very good (but occasionally quite technical) Vaillant forum on heatpumpmonitor.org  The guys there have even written up quite lengthy descriptions of what some of the Vaillant settings do and have done a fair number of well thought through measurements.  The only problem with that forum is that the 'user interface' is a bit unintuitive.  However the people on it are generally very good.

Feel free to ask questions here.  Once you get used to it the Vaillant controls are pretty good IMHO, amongst the best from what I can glean from the various manuals for others that I have read.  However as I say I rarely need to touch them.  Its a bit late in the season for you to do much tweaking, but you may have to do some a bit later in the year when it gets colder again.